Display device, manufacturing method of display device, and electrode forming method

Abstract

A display device includes: a substrate; first and second transistors provided on the substrate to be spaced apart from each other; and a display unit electrically connected to the first transistor, wherein the first transistor includes a first semiconductor layer including crystalline silicon, a first gate electrode, a first source electrode, and a first drain electrode, wherein the second transistor includes a second semiconductor layer including an oxide semiconductor, a second gate electrode, a second source electrode, and a second drain electrode, and wherein the second gate electrode includes a first layer that is provided on an insulating layer and includes molybdenum, a second layer that is provided on the first layer and includes titanium, and a third layer that is provided on the second layer and includes molybdenum.

What is claimed  1 s: 
     
         1 . A display device comprising:
 a substrate;   first and second transistors provided on the substrate to be spaced apart from each other; and   a display unit electrically connected to the first transistor,   wherein the first transistor includes a first semiconductor layer including crystalline silicon, a first gate electrode, a first source electrode, and a first drain electrode, wherein the second transistor includes a second semiconductor layer including an oxide semiconductor, a second gate electrode, a second source electrode, and a second drain electrode, and   wherein the second gate electrode includes a first layer that is provided on an insulating layer and includes molybdenum, a second layer that is provided on the first layer and includes titanium, and a third layer that is provided on the second layer and includes molybdenum.   
     
     
         2 . The display device as claimed in  claim 1 , further comprising:
 a first insulating layer provided between the first gate electrode and the first semiconductor layer;   a second insulating layer provided over the first gate electrode; and   a third insulating layer provided between the second gate electrode and the second semiconductor layer,   wherein the insulating layer is one of the second insulating layer and the third insulating layer.   
     
     
         3 . The display device as claimed in  claim 2 , wherein the second gate electrode is provided on the third insulating layer. 
     
     
         4 . The display device as claimed in  claim 3 , further comprising:
 a capacitor electrode provided on the second insulating layer; and   a fourth insulating layer covering the capacitor electrode, the fourth insulating layer being provided between the second insulating layer and the second semiconductor layer.   
     
     
         5 . The display device as claimed in  claim 4 , wherein at least one selected from the first gate electrode and the capacitor electrode includes the first layer, the second layer on the first layer, and the third layer on the second layer. 
     
     
         6 . The display device as claimed in  claim 2 , wherein the second gate electrode is provided on the second insulating layer, and the second semiconductor layer is provided on the third insulating layer. 
     
     
         7 . The display device as claimed in  claim 6 , further comprising a capacitor electrode provided on the second insulating layer, the capacitor electrode overlapping with the first gate electrode. 
     
     
         8 . The display device as claimed in  claim 7 , wherein at least one selected from the first gate electrode and the capacitor electrode includes the first layer, the second layer on the first layer, and the third layer on the second layer. 
     
     
         9 . The display device as claimed in  claim 1 , wherein the thickness of the third layer is thicker than that of the first layer. 
     
     
         10 . The display device as claimed in  claim 1 , wherein the display unit includes:
 a first electrode electrically connected to the first drain electrode;   a second electrode provided on the first electrode; and   an emitting layer provided between the first electrode and the second electrode.   
     
     
         11 . A method of manufacturing a display device, the method comprising:
 providing a first semiconductor layer including crystalline silicon on a substrate;   providing a first insulating layer over the first semiconductor layer;   providing a first gate electrode on the first insulating layer;   providing a second insulating layer over the first gate electrode;   providing, on the second insulating layer, a second semiconductor layer spaced apart from the first gate electrode, the second semiconductor layer including an oxide semiconductor;   providing a third insulating layer over the second semiconductor layer; and   providing a second gate electrode on the third insulating layer,   wherein the second gate electrode includes a first layer that is provided on the third insulating layer and includes molybdenum, a second layer that is provided on the first layer and includes titanium, and a third layer that is provided on the second layer and includes molybdenum,   wherein the providing of the second gate electrode includes:   a first etching process of etching the second layer and the third layer; and   a second etching process of etching the first layer.   
     
     
         12 . The method as claimed in  claim 11 , further comprising: between the providing of the second insulating layer and the providing of the second semiconductor layer,
 forming a capacitor electrode overlapping the first gate electrode on the second insulating layer; and   providing a fourth insulating layer provided over the capacitor electrode.   
     
     
         13 . The method as claimed in  claim 11 , wherein the etching speed of an etching gas used in the first etching process with respect to the third layer is 0.9 times to 1.1 times of that of the etching gas used in the first etching process with respect to the second layer. 
     
     
         14 . The method as claimed in  claim 13 , wherein the etching gas used in the first etching process includes sulfur hexafluoride (SF 6 ) and oxygen (O 2 ), and
 an etching gas used in the second etching process includes chlorine (Cl 2 ) and oxygen (O 2 ).   
     
     
         15 . A method of manufacturing a display device, the method comprising:
 providing a first semiconductor layer including crystalline silicon on a substrate;   providing a first insulating layer over the first semiconductor layer;   providing a first gate electrode on the first insulating layer;   providing a second insulating layer over the first gate electrode;   providing a second gate electrode spaced apart from the first gate electrode on the second insulating layer;   providing a third insulating layer over the second gate electrode; and   providing a second semiconductor layer including an oxide semiconductor on the third insulating layer,   wherein the second gate electrode includes a first layer that is provided on the third insulating layer and includes molybdenum, a second layer that is provided on the first layer and includes titanium, and a third layer that is provided on the second layer and includes molybdenum,   wherein the providing of the second gate electrode includes:   a first etching process of etching the second layer and the third layer; and   a second etching process of etching the first layer.   
     
     
         16 . The method as claimed in  claim 15 , further comprising providing a capacitor electrode that is provided on the second insulating layer, overlaps with the first gate electrode, and is simultaneously formed with the second gate electrode. 
     
     
         17 . The method as claimed in  claim 15 , wherein the etching speed of an etching gas used in the first etching process with respect to the third layer is 0.9 times to 1.1 times of that of the etching gas used in the first etching process with respect to the second layer. 
     
     
         18 . The method as claimed in  claim 17 , wherein the etching gas used in the first etching process includes sulfur hexafluoride (SF 6 ) and oxygen (O 2 ), and an etching gas used in the second etching process includes chlorine (Cl 2 ) and oxygen (O 2 ). 
     
     
         19 . A method of forming an electrode, the method comprising:
 sequentially forming a first layer that includes molybdenum, a second layer that is provided on the first layer and includes titanium, and a third layer that is provided on the second layer and includes molybdenum;   a first etching process of etching the third layer and the second layer in a lump; and   a second etching process of etching the first layer,   wherein the etching speed of an etching gas used in the first etching process with respect to the third layer is 0.9 times to 1.1 times of that of the etching gas used in the first etching process with respect to the second layer.   
     
     
         20 . The method as claimed in  claim 19 , wherein the etching gas used in the first etching process includes sulfur hexafluoride (SF 6 ) and oxygen (O 2 ), and
 an etching gas used in the second etching process includes chlorine (Cl 2 ) and oxygen (O 2 ).